May 24, 2010

(PhysOrg.com) -- Men die at higher rates than women across the lifespan. A new study suggests that this excess mortality is the price of reproductive competition.

Researchers have long known that women outlive men on average, and more recently have discovered that men have higher mortality risks across the entire lifespan. University of Michigan researcher Daniel Kruger offers this explanation: It is all about sex.

Women invest more physiologically in reproduction than men, thus men compete with other men for mating partners and try to make themselves attractive to women. This competition leads to strategies that are riskier for men both behaviorally and physiologically, and these result in higher levels of mortality.

"If mating competition is responsible for excess male mortality, then the more mating competition there is, the higher excess male mortality will be," said Kruger, an assistant research professor in the U-M School of Public Health. In the current study, Kruger shows that two factors related to the level of male reproductive competition contribute to higher rates of risk-taking and mortality.

The first factor is polygyny, the social situation in which one man maintains sexual relations with many women (the opposite is polyandry—one women and many men). Several species of primates show high levels of polygyny, where one dominant male mates with most of the females in the group, and other males are left out. Human cultures have varying degrees of polygyny, and Kruger found that the more prevalent the practice, the higher the rate of male mortality.

In a polygynous culture, men receive enormous evolutionary benefits from becoming dominant. Those guys get all the gals, almost literally. Non-dominant men are left with few, or none, to choose from. In a polygynous group, winning males reap huge rewards; everyone else gets next to nothing.

The second factor: the degree of economic inequality. In mate selection, men are valued for the resource investment that they can provide, bringing benefits their offspring. The wider the gap between rich and poor, the more likely men are to die young.In less egalitarian societies, a man with what scientists call "resource control"—money, property and economic security—is more likely to find sexual partners.

In both of these cases, there's a yawning gap between climbing to the top of the heap—either as the dominant male or the wealthiest—and falling short. To lose position in polygynous or economically extreme societies is to lose almost any chance at finding a sexual partner.

What's more, Kruger says, these two factors are related, because getting the lion's share of economic wealth is often virtually the same thing as becoming dominant male.

And so the battle to be "king of the hill" turns deadly. When winners take all, men have very little to lose—and a whole lot to gain—by risking everything to get to the top.

Kruger conducts research in the field of evolutionary psychology, the study of how present-day human thinking and behavior has been shaped by past evolutionary adaptations. It turns out that some other primates display such winner-take-all behavior, and there's a strong evolutionary reason behind it. By dominating most or all of the sexual encounters in a group, males who are higher on the social and economic ladder are more likely to pass their genes onto the next generation.

The opposite case, Kruger found, also holds true: The more egalitarian a society, and the more devoted to monogamy, the less extreme the risk taking. But no human culture, Kruger concluded, is perfectly free of such competition.

Can you judge a man’s faithfulness by his face? How about whether he would be a good father, or a good provider? Many people believe they can, according to a University of Michigan study published in the December issue ...

A camper who chases a grizzly but won't risk unprotected sex. A sky diver afraid to stand up to the boss. New research shows that not all risk is created equal and people show a mixture of both risky and non-risky behaviors. ...

In places where young women outnumber young men, research shows the hemlines rise but the marriage rates don't because the young men feel less pressure to settle down as more women compete for their affections.

Recommended for you

(Phys.org)—That there are universal patterns in the naming of colors across languages has long been a topic of discussion in a range of disciplines, including anthropology, cognitive science and linguistics. However, previous ...

It has been 20 years since Dolly the sheep was successfully cloned in Scotland, but cloning mammals remains a challenge. A new study by researchers from the U.S. and France of gene expression in developing clones now shows ...

(Phys.org)—A team of researchers with members from several institutions in China has calculated what they believe is the minimum amount of land preservation needed to sustain wild giant panda populations. In their paper ...

The differences in how male and female fruit flies resist and adapt to oxidative stress may shed new light on how age-related diseases such as Alzheimer's and Parkinson's affect men and women differently.

43 comments

I question the premise that "men are dying for sex". A casual survey will show that ascetics, celibate monks who have no part or desires in the competition for the opposite sex still died nearly at the same age of the secular males in the larger population.

I question the premise that "men are dying for sex". A casual survey will show that ascetics, celibate monks who have no part or desires in the competition for the opposite sex still died nearly at the same age of the secular males in the larger population.

Yes but you're missing a key feature of statistics.

Men who engage in higher than average amounts of sex statistically live an average of 5 years longer than normal sexual leveled men.

I question the premise that "men are dying for sex". A casual survey will show that ascetics, celibate monks who have no part or desires in the competition for the opposite sex still died nearly at the same age of the secular males in the larger population.

I think what this article says, though it doesn't just come out and say it, is that male genes, selected for their ability to make the male become the dominant male, decrease the life expectancy of that individual. For example, having big muscles, which is a genetic trait shared by nearly all men, celibate monk or not, might make men less healthy overall (more wear and tear on the body?). There could be a million small effects like that, that don't have to do directly with the actual act of competing for mates.

The part about economic disparity is really interesting. I've always wondered about the prevalence of inner city violence. Most violent crimes are committed by young males, who are obviously the demographic most engaged in competition for mates. The higher rates of inner city violence might be largely due, according to the ideas in this article, to the poor economic situation in these communities. But not because being poor makes people more violent, it just makes people compete more intensely, with higher stakes, for mates.

I believe it does, as I am sure that competition for mates has more to do with male behavior than we'd like to admit. Any husbands out there might agree with me when I say that a man will only be as bad as his wife allows him to be, or more generally, men will usually only participate in behavior that on average increases their chances of mating. If women mate with bad-a$$es, then boys will become bad-a$$es.

"Kruger conducts research in the field of evolutionary psychology, the study of how present-day human thinking and behavior has been shaped by past evolutionary adaptations."

The above referred esoteric subject is what in coming time has to be addressed as Para`Physics ( an ontological pathway between Mind to Matter) that explicates transcendental & evolutionary knowledge more better in an exquisite beauty of being with Cosmos & Nature that nurtures every entity...

As a man who has no sexual attraction to the opposite sex, why did evolution cause me to not want to compete for females like most other men?

There has never been a female that I had any physical interest in whatsoever, as I have only found other men to be attractive since an early age. What gives? There has never been any choice in the matter for me of which gender I am attracted to - I know so.

How come these evolutionary psychology articles always make people such as me feel like some sort of genetic rarity by not ever mentioning evolution's reasons for homosexual individuals?

I apologize if my post is a bit too personal and causes some to become offended.

As a man who has no sexual attraction to the opposite sex, why did evolution cause me to not want to compete for females like most other men?

There has never been a female that I had any physical interest in whatsoever, as I have only found other men to be attractive since an early age. What gives? There has never been any choice in the matter for me of which gender I am attracted to - I know so.

How come these evolutionary psychology articles always make people such as me feel like some sort of genetic rarity by not ever mentioning evolution's reasons for homosexual individuals?

I apologize if my post is a bit too personal and causes some to become offended.

I think a healthy, normal male ie hormonal and physical, usually find the opposite sex curious after the hormones kicks in at puberty. I have no judgment on your sexual orientation, but a careful recall and analysis of events in your life since you can remember may help you find answers you seek. Good luck.

How come these evolutionary psychology articles always make people such as me feel like some sort of genetic rarity by not ever mentioning evolution's reasons for homosexual individuals?

By definition you are a genetic rarity.

Homosexuality is an evolutionary dead end. While it may be present in many species it is nothing more than a random flaw, one that will never be selected for and will never become a permanent feature of any genome*.

I would say I sympathize with you, but having had several homosexual friends I think I know you would prefer I didn't say that.

(*baring societal intervention, homosexuals CAN reproduce naturally, and could be forced/coerced to, and/or if heterosexuals were prevented from the same... but it would only last as long as that artificial selection pressure was maintained.)

It would appear that the male of any species dies earlier than the female so I doubt if it is just sex but males to take more risk than women do and often these risks are taken by males to impress women. Could this be the reason several hundred males made the Darwin Award list before the first woman made the runners up list? These awards are given to those who kill themselves doing stupid things and almost everyone on the list has one thing in common, they are male. Since it is almost always a male doing this, I have to wonder why so many males think women are the inferior gender when to me it is clearly the male who is.

I've recently been reading several evolutionary psychology articles on the reasons for homosexuality in humans and animals. Some researchers theorize that it may be b/c it is a form of population control and homosexuals can take care of the offspring already around by their heterosexual family members since the homosexuals will not usually be having any children themselves.

It would appear that the male of any species dies earlier than the female so I doubt if it is just sex but males to take more risk than women do and often these risks are taken by males to impress women. Could this be the reason several hundred males made the Darwin Award list before the first woman made the runners up list? These awards are given to those who kill themselves doing stupid things and almost everyone on the list has one thing in common, they are male. Since it is almost always a male doing this, I have to wonder why so many males think women are the inferior gender when to me it is clearly the male who is.

I've recently been reading several evolutionary psychology articles on the reasons for homosexuality in humans and animals. Some researchers theorize that it may be b/c it is a form of population control and homosexuals can take care of the offspring already around by their heterosexual family members since the homosexuals will not usually be having any children themselves.

I don't buy that, the process of evolution is not concerned with population control, nor with starvation of individual members of the population.

Evolution would favor 1,000,000 births with 900,000 premature deaths due to starvation over 50,000 births with no deaths due to starvation. The #'s are for example only, the point is the more viable members of the population the better, regardless of what percentage die early for any reason.

Because of this I would think evolution would favor males who will reproduce, even if most of those offspring will die before adulthood.

I wanted to elaborate on the above, because I can see how people might not understand or might misinterpret it.

Basically, evolution almost always favors a larger number of births with a lower survival rate than a smaller number of births with a higher survival rate. This is due to the fact that a greater diversity in the gene pool is always beneficial.

Consider a group of 100 babies of which 10 will survive compared to a group of 20 babies of which 10 will survive. We can assume that, on average, the most "fit" individuals will survive, and the least fit will die. The group that started with 100 babies will end up with a group of 10 survivors that are MORE fit, on average, than the group that started out with 20... simply because there was more diversity in the population and the 10 remaining had to compete with more individuals for their survival.

Think of it like this, say you won a contest and could pick out any car you wanted for the prize, but the car had to be picked from one of two dealerships. The first dealership has 100 different types of cars, the second dealership only has 20 different types of cars.

Assuming random distribution of types of cars between dealerships you are much more likely to get a better car if you pick from the dealership with 100 types of cars than you are from the dealership with only 20 types of cars.

No I am not a feminist nor do I hate men but this is just a statement of many things. The death rate for males is higher at every age and this cannot be from stress as more males die before birth than do females. You may want to read "The Natural Superiority of Women" to learn more but if males can admit that they are the weaker gender, maybe more males can get help in the many areas they are weak in. (Not our fault it is almost all of them) It does take a real man to admit his weakness right?

Interesting. But what is considered fit? And I thought the Earth's population is way too high now and people might need to die off, so why would evolution want to create more individuals anyway?

Lastly, the way you succinctly described the theory of evolution makes everything sound like life is some sort of brutal and vicious competition for supremacy over all others. What about altruism and helping others?

I know evolution is the best theory for explaining where humans came from, but with the way you described it, you make it sound like Nazism or German fascism - the strongest and greatest must out compete and exterminate the weak. It is just a bit too disturbing for my mind to think about right now - if living is all about out competing others for survival and dominance.

@Soulless49erCome on....we are grown people, when we are mad we are just like animals, if there was no haterid and competition-there is no evolution, the evolution is faster actually where the competition if greater, and now this instinct is usefull too, this is moving the progress forward, the nature has nothing to do with Nazism, in a tribe lets say (or if you look at the chimps) a fights accur, this is how the fittest male is seen to be beter-stronger with good reflecses, the ierarhy is established and there you have pease again, well deaths accur too but rear...

if there is no competition in the population , there wont be any selection and no progress, at the end all of the species will be gone, it may seem haterid is something bad, but in nature it has its sense, after all the most important thing is survival of the species!

in a tribe lets say (or if you look at the chimps) a fights accur, this is how the fittest male is seen to be beter-stronger with good reflecses

These are speculations based on ideology.In real tribes, no fighting is necessary. That guy who brings home the most meat, that (other) guy who knows to read best the traces of the animals, and that lady who knows best which plants help you when you are sick - those are the natural leaders of the community. They have natural authority, not inherited or bought authority. Fighting only weakens the community.

Yes respect come in this ways too and each tribe has its lets say games which shows how fit or brave you are, but fights accur even in our society, in the past it were much more often, now it is pointless I agree.

Mating choice is also a factor that it seems is being overlooked here.

The least fit don't have to die for natural selection to work, they simply have to reproduce less frequently. Early death is only one mechanism that can create the disparity in reproduction rate between the more fit and the less fit which drives natural selection.

I don't like what evolution has created - I want to destroy the human race and all animals now. If I commit terrorist acts, I can play my role in helping to exterminate the human race for a better future for Earth.

I don't like what evolution has created - I want to destroy the human race and all animals now. If I commit terrorist acts, I can play my role in helping to exterminate the human race for a better future for Earth.

I often feel the same about humans. Some of the things we do as a species are despicable.

Of course that has nothing to do with anything. Evolution is a dumb process, it just happens as naturally as any other physical process without any kind of thought or concern for anything.

Do you think a bolt of lightning feels bad for destroying a tree? Or that the snow and ice of an avalanche mourns the animals it kills in it's wake? Evolution is the same, it doesn't matter what you think of it or of the results, good and bad is irrelevant here. Pleasure, happiness, suffering, and misery are all irrelevant to the process, and as intelligent beings all we can do is make the best out of what we have and what we are.

You would have to link that to a disparity in rate of reproduction on a per case basis.

I don't think it's that easy. While I'm convinced there is feedback between the emotional states of a population and "the process", unfortunately I can't make up any relationship as long as there's no mathematical measure for pleasure, happiness, suffering.

Well, I can see that an aspect of happiness is security. A feeling of security comes when you are relatively safe from danger. If you are relatively safe from danger you may have a higher chance to successfully reproduce than others who are not.

Viola... a potential partial mechanism for the evolutionary selection of happiness.

Of course a general feeling of happiness requires more than just physical security... but it's a start.

However, my point was not that happiness or misery or any of that could not be favored by evolution... it was that it doesn't care, it is unfeeling, if misery and suffering created more fit offspring than those would be selected for.

Well, I can see that an aspect of happiness is security. A feeling of security comes when you are relatively safe from danger. If you are relatively safe from danger you may have a higher chance to successfully reproduce than others who are not.

Viola... a potential partial mechanism for the evolutionary selection of happiness.

Of course a general feeling of happiness requires more than just physical security... but it's a start.

Good thinking but when you look the reality it is exactly the oposit, during war and crisis you have pic in the birht, you can see that in Africa, and in Europe it is the oposit situation, allso the minority grups which are feeling less protected are giving birth in great rates....the population aging is really sad, more and more people will start to come from all over to fill the gap, I am not a rasist but this is sad...and against any logic- the more you have the less you are reprodusing!

I actually cant catch what is the thinking of the people to make more children when the period is hard and unsecure, I dont think that in a period of war you have more resourses, actually the oposite, maybe it just happens unintentionaly , no planing....or maybe it is something in the humans psihology that I havent experiansed

I actually cant catch what is the thinking of the people to make more children when the period is hard and unsecure, I dont think that in a period of war you have more resourses, actually the oposite, maybe it just happens unintentionaly , no planing....or maybe it is something in the humans psihology that I havent experiansed

Well, that's easy: If you don't have many ressources, i.e. you are poor and you can't afford machines to do the work on your fields when you're old, then you need (lots of) children. The more children you have, the more will care for you when you are in need.

Oh ho who's the feminist that wrote this prize? Women need sex less than men? That's tough to swallow. I've never met a female that didn't get ready for sex every time she goes anywhere or does anything. Convience store? Dressed for sex. Class? Sexing it up. Taking an innocent walk in the park with her dog? Fiending for sex.

It is poslible actually, the most simple explanation is the right one, I havent tought from the practical side of this issue...

Huh? That's not the aphorism. Occam basically stated that the best theorem should consist of the fewest number of elements needed to explain the observed phenomenon accurately. It was taken to mean that bad theories are often overly complex to cover for incorrect first order order assumptions. For example it is widely agreed that Ptolemy's model of the solar system was overly complex (through the use of a relatively large number of epicycles) compared to Copernicus's helio-centric model.

That being said the vast majority of theories are incredibly complex. Our current model of the universe is probably much closer to the truth than the Genesis model, though it is far less intuitive.

I actually cant catch what is the thinking of the people to make more children when the period is hard and unsecure, I dont think that in a period of war you have more resourses, actually the oposite, maybe it just happens unintentionaly , no planing....or maybe it is something in the humans psihology that I havent experiansed

It is biological imperative. Humans only shine in groups. When the group is quickly depleted, the biological drive to breed kicks into high gear. This explains the boom in births during wartimes, famines, points of high crimes. Keep in mind, births don't always equate to offspring. IN some times of crisis, like famine, as I mentioned above. There are many births, but few of them produce viable offspring due to undue physical stress of low caloric diets.

It is biological imperative. Humans only shine in groups. When the group is quickly depleted, the biological drive to breed kicks into high gear. This explains the boom in births during wartimes...

Humans shine in groups? It'd be lovely if that were true. As individuals, or in small cooperatives, people are the paragon of animals, noble in reason, infinite in faculty. In large groups they are the lowest savages.

Humans shine in groups? It'd be lovely if that were true. As individuals, or in small cooperatives, people are the paragon of animals, noble in reason, infinite in faculty. In large groups they are the lowest savages.

Our civil manners and ethics are still evolving.

Biologically we're utterly unimpressive alone.

Tiger vs a single human=well fed tiger, 100% probability.Tiger vs a group of humans who're working together typically=dead tiger.

I don't believe in this. This was done on a very limited set of theories. Remember we are dealing with humans here. How about homosexuals who are dying to have sex with their own kind and their motive to compete. They were not included. Besides this theory has been studied in fishes. Female fishes outlive male fishes also one the reasons here is reproductive aspect. I don't think this is new. But his failure to compare his study with lower forms like fishes make this research output a second rate reference. This phenomenon is not new.

Please sign in to add a comment.
Registration is free, and takes less than a minute.
Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.